Automatic telephone system.



A H. DYSON.

AUTOMATIC TELEPHONE SYSTEM,

APPLICATION FILED AUG. I9. I90]. 7

- Patented Feb. 19, 1918.

1a suing-shin u.

A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM. Y Arrlllfianmd FILED AUG. In. 1901.1,257,283. Patented Feb. 19,1918.

' l3 SHEETS-SHEET 2.

A. H. DYSON. AUTOMATIC TELEPHONE SYSTEM.

, APPLICATION FILED AUG. 19. 1901. 1,257,283. Patented Feb.19,1918.

l3 SHEETS-SHEET a.

A. H. DYSON.

I AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG.I8,'I91- Patented Feb. 19,1918.

I3 SHEETS-SHEET 4.

A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

v APPLICATION FILED AUG-19,1907. 1,257,283. Patented Feb. 19, 1918.

I3 SHEETSr-SHEET 5- A. H. ovson, AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG. 19, \901- Patented Feb.19,1918.

3 SHEETS-SHEET 6.

i A. HQDYSON. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG. 19. 1907- 12573283. v Patented Feb. 19,1918.

l3 SHEETS-SHEET 7.

mwl Q ZW 'A. H. DYSUN.

AUTOMATIC TELEPHONE SYSTEM.

, APPLICATION FILE D AUG.19. 190T- Patented Feb.19,1918.

I 3 SHEETS-SHEET 8- A. H. DYSON.

AUTOMATIC TELEPHONE 'sYsTEMi I APPLICATION HLED AUG. 19. I907. I

1,257,283. Patented Feb. 19,1918.

finatmm A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION men AUG. I9. 1901.

1,257,283. Patented Feb. 19.1918.

13 SHEET$SHEET I0.

.mm f m m. N \k IE 0 7 mm 1 M; FR d n on P A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED AUG. I9. I90].

Patented Feb. 19, 1918.

I3 SHEETS-SHEET I2.

' A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

A'FPLIICATION FILED AHG.I9. 1901.

Patented Feb. 19, 1918;

13 SHEETS-SHEET I3,

UNITED STATES.

PATENT OFFICE.

ALFRED H. DYSON, OF CHICAGO, ILLINOIS, ASSIGNOB, BY MESNE ASSIGNMENTS,TO KELLOGG SWITCHBOARD & SUPPLY COMPANY, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Febr19, 1918.

Application filed August 19, 1907. Serial- No. 389,180.

To all whom it may concern Be it known that I, ALFRED H. Dyson,

, a citizen of the United States, residing at one hundred firstselectors and the wipers Ohica 'o, in the county of Cook and Stateof-Il'hnois, have invented new and useful Improvements in AutomaticTelephone Systeiiis, of which the following is a specification.

The present invention relates to automatic telephone systems generally,and has to do more particularly with that type which the well knownselector and connector switches of the two dimension type of the art areemployed in conjunction with similarly constructed line selectorscontrolled by master switches. In such systems the movable contacts, orwipers, of the two dimension switch are associated with a large numberof fixed, or passive, contacts arranged in a bank and the wipersarefirst given a movement in one direction followed by-a movement at anangle thereto, the former, or primary, movement. bring'ing the wipers toa desired group of bank contacts and the latter, or secondary,- movementcausing the wipers to engage desired bank contacts in' the selectedgroup. The connections among the different switches will be bestunderstood by discussing a. par ticular case. Thus if one hundred pointswitchesbe employed in a ten thousand line exchange system arranged on abasis of ten per cent. trunking, there would be one hundredmaster-switches, one thousand line selectors, one thousand first.selectors, one thousand second selectors, and one thousand connectors;each subscribers line would be multipled to ten line selectors and tenconnectors; the line selectors and first selectors would be united inpairs without multiplmg; the wipers of the second sel'ectors would bemultipled tothe banlccontacts of of each connector would be nuiltipledto the bank contacts of one hundred second selectors. Obviously withdifferent assumptions, values differing f1'om -tl1e above would be used,but this specific example will suflice to indicate the character of thesystem .to which my invention belongs.

In systems of this character heretofore proposed, the construction ofthe switches and the associated circuits have been such that the properoperation of the system was possible only by the employment of more orless complicated mechanism. For

example, it is common in such'systems to have certain contacts thrown toone position upon the first movement of the switch wipers and thenrestored upon the operation of a release magnet. This results in moreorless complication of parts. Other similar features might be pointed outbut this example will suflice to shOW the character of the com=plications referred to.

One of the principal objects of the present invention is to devise asystem of the character indicated which s'li'all be free of these Iobjections. This is preferably accomplished by the use of simpleswitches, having simple driving and release mechanism, combined.

with a novel arrangement of circuits in which ordinary relays-areemployed to bring about the desired results.

Another object of the invention is to extend this simplification ofstructures to all commercial adaptations of the straight automaticsystem so as to include trunking between exchange, nickel-in-the-slotservice, measured service, party line service of different kinds, aswell as unlimited service.

Still another object of the invention is to devise a novel arrangementof electrical connections between the switches'whereby the chances ofthe calling line finding an idle trunkthrough which to extend itscircuits are greatly increased.

The invention also includes other feat/1111135 and details which,together with the above, will be more fully understood .u on referenceto the following detailed escript ion taken in connection with theaccompanying I Referring to the drawings, Figure.- 1,

which is the principal figure and includes parts 1, 2 and 3, illustratesdiagrammatically an automatic telephone system embodying certainfeatures of the present invention; Fig. 2 illustrates a trunkin circuitprovided with a repeater and designed to connect exchanges located atsome disof a number of trunks running' to a given private exchange, orto a roup of telehones having a single ca ling numberfii iigs. 5', 6 and7 illustrate connector circuits designed foruse with party lines, thelatter illustrating in addition a four-party subscribers line; Fig. 8illustrates a modified slot service substation and line circuit; Fig. 9illustrates a novel method of interconnecting and trunking betweenswitches by which the chances of a cal-ling party obtaining a desiredconnection are increased; Pigs. 10-,11 and 12 are elevationsof a lineselector viewed from different Sides, the switch bein also typical'ofthe other selec tors and t e connectors *en'iployed in the system; Fig;13is a plan view of said switch; Fig. 14 is a sectional plan of aportion of the same taken on a plane indicated by the line l i -14L ofFig. 11; Fig. 15--i'a detail "iew of certain connector off-normalcontacts; Fi s. 16 and 17 are front and side eleyations o an1aster-switeh en'iployed in the control of theline selectors; Figs. I8and 19 are front and sectional elevaticms, respectively, of a ringingmachineeniployed in con nection vith certain of the party line clrcults;Flgs. 20. and 21 are. front and rear elevations, respectively, of metermechanism employed for nleasured service; amlFigs.

and 23 are front and side elevations respecpartyln ie use.

Mai/L system. Apparatus,

Referring to the drawing, and more particularly for the present to Fig.l, which may be considered the main diagram, M at the left oi' tliodiagram designates a subscribcrs station provided, with fslofi equipmentand united to the main exchange by the line limbs l'f andH whichttrll'li'l'ltlll. in multiple contacts of line connectorsnnd lineselectors. At the opposite end of the dia gram, N dcsignatcsasubscriber-s equipment which is not c signed for slot s1 twice and whichis si1nilarly unitedv by line Qliinbs l-S' to the exchange andihc linelimbs are similarly.connected toitl1e ,lllillll l'llclt'mk lacts ofconnectorsand lin'e selectors. lonuection. is obtained between the lineat the left and the line at the'right through the agency of amaster-switch (),a line selector Q, a first selector U, a secondselect-or- V aud" a connector. \V. Assuming that. the sclecto rs andconnectors employed in. establishing this connectionare provided withone lulnd'rei'l bank' contten thousand lines in the exchange arranged ona basis of ten per cent, trunking, then, the

Throughout-these views like characters refer to like parts.

I with the thousalulgroup-to which the c and assliuningthat there arenumber of switches and their multiple zirrangement heretofore outlinedwill exist. In such case there would be one-hundredni terfswitches 0.one thousand line selectors Q, one thousand first selectors U, onethousand second selectors V and one thousand connectors V. Thesubscribers lines would be dis rided into groups of one hundred, and tenline'selecting switches would be assigned to each group, thu enablingeach line to be multiplcd to the corresponding bank eon tacts on tendill'erenf line selectors. Each group of line selectors would be underthe. control of one masterswiteh, having-a pair: of bank contactsassigned to each lineselee; tor. Each subscribers line would'alsoniultipled to "the corresponding bank contacts of ten connectors. In thediagram, only two of the ten sets of multiple contacts of the lineselectors and cornice-tors are-illus tratcd, while but five pairs ofbank eon. facts of the master-switch are slniwn. The I movable contacts,or 1 wipcrsg of each line selecting switch Q. are tied to thecorresponding' wipers of a first selector ll, thus prov 9o ridingonc'thousand dilccl connections"be tween the one thousand line selectorsand the one thousand first selectors. The wipers of the second selectorsare multiply connect- 1 ed to the bank contacts of" the-firstselectorsand'since' there area thousand oteaehof these switches, thewipers of each-second sclector' are connected to, the corrcsponding.vcontacts 0t one hundred firstselech'n's. S'i1n-,.

sets an idle line selector Q, in operation to aulon'iatuzally seek out.and establish wa ncction with his line, thus extend ngthe calling linecircuit to the first selector EU. paired with the actii'atcd lineselector Q.'-.]L5yr The calling party thenyby mounsof his call in;mechanism, transrriits a number. of. ini pulses corresponding; to the'digits '0' lunlnnbcr ol the subscriber a.nte(l.. 'llhr st series ofthese impulses opcratcsjlu; corn/12b, ;v

ncctcd first selector so aslomauscit to pick out an idlesocoiul selectorassociated l lcd line belongs. Thug if the number of theeall-g ing partywere two thousan l fiolne odd, the 1:25

first set of two impulses would JlLo-V wipers of the first selectorgroup of its bank, contacts and wouh I automatically more the wipers o\"cr,the'con;- tacts in this bankuntil an idle eont a t i i i Eli:

ilarl \",'thc wipers/of each of the thousandLlQD lhrough the agency ofthe master-switch 0-, lie

encountered, thereby extending the circuit of the calling party to anidle second selector in the second thousand group. The sec ond series ofimpulses would similarly operate the second selector V to pick out andes tablish connection with a connector associated with the hundredsgroup to which the called line belongs. Thus if three impulses weretransmitted over the circuit, the second selector V would move itswipers to the third group of its bank contacts and the wiperswouldthen-automatically move overthe contacts in this bank until an idleone was selected, thereby extending the circuit of the calling line to aconnector having access to the called line. The third series of impulseswould cause the connector to move its wipers to that group of tencontacts in which the contacts of the called line were included, and thefinal series of impulses would cause the Wipers to move over thecontacts in this roup until thecontacts corresponding to t e called linewere encountered, thus completing the connection between the calling andthe called lines.

Each line is provided at the exchange with a line relay LR which isinstrumental in closing a circuit through the masterswitch 0 upon theinitiation of acall, and a'cut-ofi relay G0 which is used to destroy thenormal substation control of the line relay and to otherwise vary theline connections.

The master-switch 0 comprises a pair of wipers 20-21 cooperating withbank contacts 22-23 and caused to step over said contacts by a motormagnet MM the comlete operation being controlled b the-reays 2%25, ashereinafter'more fu ly pointed out.-

The line selector includes the wipers 26, 27, 28 and 29 cooperating withbank contacts 30, 31, 32, 33 and, where the meter mechanism X is used,with an additional wiper 34 cooperating with bank contacts 35 as.willappear from Figs. 9 to 13 inclusive, described more fullyhereinafter.

'26, 27, 28 and Y34 partake of the two movements of the switch, that is,the primary and secondary movements, while wiper 29 Wipers partakesonly: of the primary movement.

The primary movement of the wi ers is brought about by primary magnet PCOD- ' trolled by a primary, relay PR, and its secondary movements issimilarly brought about-by a secondary'magnet SM controlled by asecondary relay SR, while the release of theswitch, which permits it toreturn to 1ts normal position, is brought about by a release magnet RMcontrolled by a release relay RR. The switch is also provided withprimary and secondary oil-normal contacts-- PO and SO which are operatedrespectiveily:

. upon thei first primary and the first secon {try movements of theswitch. Although contacts of two connectors;

The first selector ,U includes the wipers 39, 40, 41 which cooperatewith bank con tacts 42, 43, 44 in response to the operation of theprimary Ina net PM, controlled by the pllnltiI/P' relay R, and thesecondary magnet S controlled by the secondary relays SR and SR'.- Thewipers in this case all partake of the primary and secondary movementsand the switch is released through the operation of the release magnetRM and the release relayRR'. The pri mary off-normal contacts PO andsecondary off-normal contacts SO here, as before, are operated upon thefirst primary and secondary movements of the wipers respectively. Thecircuit associated with this selector also includes a reversing relay RVfor reversing the direction of current supplied to the calling line andan associated relay 45, all of which will be more fully understood fromthe subsequent descriptlon.

The second selector-V comprises wipers 46, 47, 48 which cooperate withbank con tacts 49, 50, 51 in the same manner as the first selector U. Inthis case, the corresponding relay, magnets and off-normal contacts aredesignated by corresponding reference characters having the exponent 2-instead-of 1.

The connector W is provided with wiperswith-a busy relay BR, a ringingrelay RG,

a control relay R, a tip relay .TR, a flip- In addi-' flop relay FF, anda closing relay OR,

all of which cooperate in the manner heremafter more fully set forth. 7

a As in the case of the line PS, the line P-S is provided with a cut-offrelay CO and a line relay LR.

In this fi are I have also illustrated mechanism or recording thecompleted connection over each calling line. One of these meehanisms isassociated with each linezselector and comprises 'a printi ng magnet 58,a .type wheel 59, actuated by a motor magnet MM controlled by relays 60,

(it and wiper 62 rotated with the type wheel Jiland cooperating:withbanlr 'contacts 63 of whichthere'cisxa number equal'to. the nun'iber;ot-contaets 35011 the line selectors.

The .equipn rcnt at substation i\'["inc1udes the usual-switchhook 64s,receiver 65, callbell 456,41 nsmitter -67, calling mechanism tiS and sotmechanism 69 including a. polarized relay 70. The equipment atsubstation; differs from that at substation M by olnittii'ig the"slotmechanism (3!),

Obviously, the various subscribers lines enter-int "the exchai'ige willbe distributed through the agency of a distributing board which Iylunteindicated at the points desig 11ated-y.D-B. Many di-tl'erel'tt methodsof distributingmaybe employed, but I preferably distribute: the linelimbs and :the'

hook tit and.thereby. establishes a circuit which maybe tl'fltttltl lhfilll the live, or negatire, pole of the battery llthrougrh rcsistzinccTl, clostal contact T6 of outwit relay (.70, line limb S, closedcontact. 75. the windin; of. lock, controlling magnet 74, switchhooktil. transmitter (3?, closed contact 73,

line limb l, Iiormalconlaet 72 of cut-off re lay (It), normal et-sntact;77 of line relay LR, and the winding ol said. relay to the ground.- ed;or return side of the battery. The resulting nloy ement ot' the bent act77 toits alternate position closes-a new energizing circuit for the linerel ay LR which may be traced from the live, or negative, pole of thebattery JV-tlnrongh the winding of relay 24. of the.1nastrr switcl1 0,closed Contact T8 of t-nt otl' relay (0 and alternate contact 77 0'' lino relay Lift through the winding of said relay to grount-l. The closingof this circuit continues the energization of the l ne relay andactuatesrelay 12 t .so as to close itscontact it) to, omplete a startingcircuit for one of the line selectorsQ, as will he hereinaftereaplainedf ,The movement oi contact 80. of 11111 30-30." this g throughnormal contae corresponding t ,o the calling line; ;1d ,eoimection.normally ,xisting 91 0f. out et? relay elay .LRJr emovcs the non malgroiu d coi'mection from therontact-s CO and normal contact 80 of linerelay LR. in addition to the removal of this ground 'n'hich establishesthat condition which will cause the line selector wipers to stop inengagement with the contacts of the line aller they have been moved tothe desired group, the actuated contact 80 of the line relay, groundsthe winding of relay 82, which, upon being energized, opens its contact83 to remove the normal ground from those contacts 3333, etc.,whichteorrespend to the group of contacts in which those of the callingline are located, thereby establishing that condition which will causethe line selector to stop its primary movement at the proper group ofbank contacts. The contact 84: of the line relayupon"being attracted,destroys the normal battery con nection through the winding of thecut-oft" relay GO to the contacts 36-36, etc, of the connectors to whichthe line P'S is connected, and substitutes a ground. connec-- tiontherefor. As will be hereinafter explained, the normal. batteryconnection to these contacts permits connectiorrto be made to the linePS as a called line, While the ground connection renders the said linebusy to lIl-COIIIlIlg calls.

The mastenswitch wipers 2021 are brought, after each operation of a linesc lector Q, into engagement with contacts 22-23 assigned to an'idle'line' selector as will be hereinafter explained- -Thus, as soon asrelay 24 is energized, a starting circuit for silch line. selector iscompleted by the closing-of battery B through the winding of primaryrelayPR, primary'offnormal contact 85, contacts 22-20, closed contact79, andnormal contact 86 to ground,

thus energizing primary relayPR to actnate its contacts and therebycomplete a cir cuit' from the. live pole of the alternating currentgenerator 87 through the winding of primary magnet PM and alternate contact S8 of primary relay IRto ground,'thus causing the wipers 26, 27,.28, 29 and 34 to more in a. primary direction. The said group relay 82has its Winding connected to a plurality of alternate contactsSO,

indicated by the symbol (which sign serves throughout the drawing toindicatd a. common connecting point), on as :many different line relaysLR. Thus,1in thee x ample-chosen, there would be one hundred line relaysand ten group relaysfor a grou p of one hundred calling lines. Eachgroup of the switch wipers, the initial energizing f circuit of theprimary relay PR is inter-- rupted, but in the meantime the closing of,

contact 89 of said relay has completed a new path through wiper 29 whichis maintained circu t at all times except when an ungrounded contact 38is engaged. It should also be noted that although the wiper 29 isnormally out of engagement with contact 33, it engages said contact atthe time the primary off-normal contact 85 breaks, thus insuring asuitable circuit for the relay PR until the wipers have been moved tothat group of bank contacts which included the contacts assigned to thecalling line. Just as soon as this group of contacts is reached, theprimary movement of the switch wipers will be discontinued and thecontacts 88-89 of relay PR will return to normal. The return of contact88 will immediately energize the secondary relay SR over a circuitextending from the live pole of battery B through the winding of saidrelay, a secondary off-normal contact'90, primary cit-normal contact 91,which is closed at this time, and closed contact 88 to ground. Themovement of contact 92. of relay SR to its alternate position, will atonce close an 81161: gizing circuit for the secondary magnet bMextending from the live pole of the alternating current generator ,93through the winding of the secondary magnet, alternate contact 92, andnormal contact 94 of wipers will continue until amungrounded contact. Sncethe contact release relay RR to ground. The resulting repeatedenergizations and dcenergizations of the'seeondary magnet Will cause theswitch wipers 26, 27, 28 and 34; to move in a secondary direction overthe contacts 30, 31, 32 and 35, respectively, of that group of bankcontacts including the contacts of the calling line. Since upon thefirst secondary movement the contacts of the secondary off-normal switchS0 are actuated, the initial energizing circuit of'jthe relay SR will beinterrupted but in the meantime the closing of its contact 95 willprovide a new path through normal contact 96 of release magnet RM towiper 26, and

thence 'to ground so long as said wiper engages a grounded contaet 30.;It W1l1 be noted in this case as in t e case ofwiB 29 that the end ofthe wiper is prefera madebroad enough to bridge the space be tweencontiguous contacts and that although normally out of engagement withthe nearest bank contact, it will engage said contact by the time thesecondary off-normal contacts are moved from normal the secondarymovement of the switch ment.

bridges and thereby energize relays Thus,

wiper 26 engages.

30 corresponding to the calling line has been wipers will be stopped inengagement with the contacts corresponding to said line. Since othersubscribers lines are multiply connected to contacts over which thewipers 27-28 pass during this secondary movement, and since conversationmay be going on over a connection including said contacts, the relay SRis arranged to electrically disconnect the wipers 27-28 from other partsduring this secondary move- This is brought about by contacts 96- 97,'which in their normal positions, join the adjacent portions of thestrands or conductors LL', but when actuated, separate them,thusdisconnecting the said wipers from other parts. Thus, as soon as thewiper 26 engages an ungrounded contact 30, the relay SR is deenergizedand the contacts 92, 95, 96, 97, return to-their normal positionsthereby discontinuing the further secondary-movements of the wipers andrestoring the normal connections of the wipers 27-28. The contacts 9697of relay SR when in their alternate positions connect the right-handportions of the strands LL by a bridge which includes alternate contact96, closed'contact 98 of release relay RR and alternate contact 97. Thesame portions of the strands L-L are united by a bridge including normalcontacts 99-400 of reverse relay RV, windings of primary and secondaryrelays PR and SR and batteries bb. These batteries being Y arranged inseries, supply current over a circuit including both of these PR and SRto actuate their contacts. This prevents the possible closing of therelease circuit (when the secondary off-normal contacts SO .areactuated) from battery 13 through the winding of release relay RR,closed contactlOl, contacts l02103,of relays PR and SR and the windingof release relay RR of the first selector U to ground.

Thdrestoration of the contact 92 to nor- I mal, since the .contact 104of the secondary off-normal switch S0 is now closed, immediatelycompletes-a circuit which" is instrumental in causing themovement of the master-switch O :to engage contacts of an idle lineselector. This circuit extends from ground at contact 94 of releaserelay RR through said normal cont-act 92, closed contact-104, contacts"2321 of the master- Due to the mechanical relation of the parts,

the energization and deenergization of this n'iagnet will step thewipers 2021 into engagement with the/ next pair of bank contacts.

' this pair is in use, there exists a ground at one point or another, aswill be explained, on the corresponding contact 23 wluch Wlll maintainthe relay energized and thereby maintain the circuit for the motormagnet. As soon, however, as an ungrounded contact 23 1s encountered,thisenergizlng circuit for relay 25 will be interrupted. Contact 23corresponding to a busy line selcctor will always be grounded, whilethat corresponding to an idle line selector will .be ungrounded, thusinsuring the stopping ofthe master-switch with its wipers in engagementwith contacts eorrespoiuhng to an idle lmesclector. the groundconnection with, the contact 23 may exist over the path just tracedincluding contacts 104, 9'2, 91, or by Way of alternate contact 96,alternate contact a") closed contact no closed contact 91 and'alternatecontact be to ground. ()r the said ground may be maintained through theoff-normal contact 136 ot the primary oil-normal switch P0 of the firstselector U, or at other times through closed contact vi .178 of thereversing relay RV and closed contact 1740f relay 45.

;As soon as the secondary relay SR of the line sclector has beendeiinergized, and the 1 adjacent portions of the conducting strands L-,Lunited, there are at once established circuits for the primary andsecondary rclays P11 and SR 111 l eu ot that previously traced throughthe alternate contacts 9(3'-9T "of relay SR. Thus a circuit extends fromi the, live, or negative, pole of battery B ,tl-irouglrthe winding ofthe cut-off relay G0,

contact 10t3-107 of said relay, bank contacts 31, wiper 27, strand L,normal contact 99 of reversing relay RV, winding of primary .relay PR tothe live, or positive, pole of grounded battery I). At the same time, acircuit is completed from the ive, or negative, pole of battery I)through tl1ewiud-' in g of secondary relay SR, normal contact I100 .ofreversing relay RV, strand L ineluding contact 97, wiper 28, contact 32,line lianb- 13, via normal contact 7t; and coil 71 .to the negative poleof battery ll prior to the operation of cut-oft relay Ct) andimmediatelysubscqneirt thereto, over line. limb S, contact 75, lockmagnet. 74, SW]t.-Cl1-llOOl (it,

,.transmitter(l7, contact 73, line limb l, in-

orll-ulingalternate contact 7:3 of cut-oil relay tt), contact 31., wiper27, l nk strand L, in rlrulillg contact tlti. normal contact 99 ot rerel-sing relay RV, the winding of pril-nary .relayfllli' to tluyposith epole of battery I). flho cl sing of these cu'clnts maintains the relayslli-ijllltlhbli' energized, and in addi- ,tion: energizes the cut-otl'relay t) and the lock eontrollio g,.Iuagnet 74 associated with thecalling line. 'The movementot contact If the line selector correspondingto i 72 of the cut-Ofi' relay to its alternate posi tion continues linelimb P to contacts 31 -31 and interrupts the initial energizing circuitof the line relay LR and thus destroys the normal substation control ofsaid relay. The opening of its contact 78 likewise interrupts thecircuit established through relay Bat of the master-switch and the linerelay. The opening of contact 76 interrupts the normal connection ofbatteryB' to the line limb S. Thesubscribers circuit is thus completedover the heavily marked lines to the sections of the strands LLlyingbeyond the condensers l08-109. The movement of contact 81 interrupts thepath for current over the strand L through the cut-off role) 00, butbefore said circuit is interrupted, a new circuit is provided for thecut-elf relay CO, which extends from lmt'tery B through the winding ofcut-oft relay, contacts 107,81, engaged contact 30, wiper 26, normalcontacts 96 and 95, and winding of relay 61 of the meter mechanism X, toground. Thus the cut-oil relay (0 is maintained energized. The guardingcircuit to ground for the line selector con.

tacts 30, 30, etc, and for the connector con, tacts 3G, 36, etc.. is nowfurnished through said relay 61 as follows :fro :1 contacts 36 vianormal contact 84, alternate contact 81 and'said contacts 30, 30, etc.,and thence to ground through said relay (51 over the circuit p'rcriouslytraced for holding the cutoll'relay (It) energized. Upon closing thiscircuit the meter mechanism X is set in operation to move its wiper 62and the rigidly connected type wheel 59 to that position correspondingto the calling line P c. This is brought about by the energization ofrelay (31, which completes a circuit for the motor magnet MM extendingfrom the live pole of the alternating current generator 109 through thewinding of said motor magnet, closed Contact 110 of relay (l1 and closedcontact. 111 of relay 60 to ground.

The wiper (S2 is thus moved over the bank contacts 63 which are'eqHaI innumber to the line selector bank contacts 35. These contacts arepreferably arranged in a circle so that the wiper (32 need hare but asimple rotary motion. Corresponding contacts 35 and 63 are electricallyconnected and since wipers 3i and 26 are connected. there exists at thistime a potential at the contact (33 'correspoluling to the calling line.which will be above that of ground and. consequently, as soon as wiperG2 in its more-- uleut engages this contact 63,11 circuit will becompleted from contact (33, through wiper (i2, \\'iudiug of relay tit)and closed contact (51' of relay (it to ground. \rhereby relay (i0 willbe energized and its contact '1l1 opened to thereby interrupt thecircuit of the motor magnet MM and thus discoutinue further movement ofthe wiper. By

' zation of said line relay I lease of relay 24 of the master-switch 0unmeans of contact 61', the ground connection with wiper.62, and thenceto contacts 63, 35 and 30 of the particular switch in use, is removedupon the release of theswitch and subsequent improper operation, dueto'the presence of such a ground, is thereby prevented. From this itwill be seen that the wiper 62 and the type wheel 59 are moved to adefinite position corresponding to that of the calling line and left inthat position. As will appear more fully hereinafter, as soon as thedesired connection with the line PS is'complete, the printing magnet 58will be energized and there will be placed on a recording sheet, a typeimpression corresponding to the calling line, as for example, the numberof the calling line. The disconnection, and consequent deenergization,of line relay LR causes the release of the group relay 82 unless therebe another line relay, belonging to the same sub-group of ten, energizedat this time for the purpose of also initiating. a'call. Assuming nosuch condition to exist, the releaseof relay 82 will restore the groundvia contact 83 to bank contact 33 and to the other multiple contacts onthe nine other line selectors,

thereby permitting wipers 29 of said other line selectors to rotate pastthe sub-group containing the calling line Whose call has now been pickedup. Also the denergi- LR causes the re less "there be at that timeanother line relay belonging to the same group of one hundredsubscribers then initiating a call. Assuming there be no such other callexisting, the release of such relay 24 will prevent the starting ofanother line selector when the master-switch steps its wipers 20-21around to engage the bank contacts corresponding to the next idle lineselector.

With the parts in this position, then it remains for the calling partyto operate his calling mechanism 68' to send the necessary impulses toextend his circuit to that. of the called line. The calling mechanism isdiaranunatically represented by a disk having a number of teeth adaptedto engageasprmg 73' to cause to break contact upon the return of thedisk due to return spring 112,

and a single tooth similarly cooperating with contact spring 75 to causeit to open its contact after the contact 78 has completed itsinterruptions. The disk is also with a pin which engages a springcontact 113 to hold it out of engagement with a similar spring contact114 and a grounded contact 115.

locked by means of a hook 116 arranged to en 'age a notch in the diskand normally.

held in engaging position by a spring and move out of engaging positionby the ener: gizations of the magnet 74. In operation, the disk-11smoved against the tension of the the diagram,

The disk is normally.

manner as substation N, that is without theslot mechanism 69, the callinparty would now be free to operate his dlal to. send the necessaryimpulses. In the present instance, however, any break which might bemade by contact 73 would be bridged by normal contact 116' of the slotmechanism so that there would be no resulting interruption of the linelimb P as would be necessary to cause the operation of the connectedfirst selector; consequently it is necessary forthe calling party todeposit a nickel or other token in the slot of the slot mechanism 69.When thisis done, the contact 116 is forced by the tzoken to itsalternate position. This is accomplished in the present instance byhaving a suitable projection from the con tact 116 extend into theslot'. .As indicated upon the lower portion of the substation dia gram,the pivoted end of the switch-hook is provided with an upward projection117 which engages the lower end of a pivoted arm 118 which is adapted tobe moved in the slot in order to determine the disposalrelay 70, whichin normal position bears against a fixed stop. In case the connection iscompleted, the polarized relay is energized by a reversal of current,caused by the operation of the reversing relay. RV,'to throw the upperend of the arm 118 to the left to collect the token by allowing it topass downward through the right-hand outlet of the slot, into a suitablereceptacle. In case the desired connection is not completed, the tokenis returned upon the restoration of the receiver to its hook whichforces the arm 118 to the right to the position indicated in therebyallowing the token to pass out of the left-hand outlet of the slot intoa suitable holder. from which it may be taken by the calling party.

Assuming now that the calling party has deposited his token and therebyinterrupted a bridge about the contact 73, he will be at allow it toreturn to its normal position-andhe will follow this operation bysimilar operations :in'whichhc will rotate the dial suifibring threeteeth below the con-

